The effectiveness of emergency services resides in the ability of the service to deliver the telephone number and location information of the caller seeking assistance to the appropriate emergency services personnel, such as police, fire, and medical assistance. Emergency services have evolved to accommodate and adapt to the gradual emergence of mobile communication services over traditional wired landline telephone services. For example, the 911 service in the United States has been modified to what is now referred to as enhanced 911 (E911) in order to allow licensed wireless network operators the capability to provide location information of a licensed wireless caller to the appropriate emergency services personnel.
Traditional wired telephone landlines have associated physical address locations making the identification of emergency calls from such locations a relatively trivial matter. When the emergency call is placed from a landline, the call is routed to an assigned local Public Safety Access Point (PSAP) that is closest to the caller. Prior to dispatching the call to the PSAP, the telephone number of the caller is used to query an Automatic Location Identification (ALI) database. The telephone number or an associated index is passed to the PSAP which then uses the information to retrieve the location or address associated with the telephone number from the ALI database. This information then permits emergency dispatchers to coordinate and send the appropriate emergency personnel to assist the caller.
Such emergency services had to be refined to become compatible with the emergence of mobile communication technology. Mobile communication devices, such as cellular telephones, wireless-enabled personal digital assistants, and the like no longer confined callers to a physical address when placing calls. In fact, the mobile devices allowed the callers to cross PSAP regions, cities, states, and even countries. Therefore, in creating the new integrated emergency systems, various regulations were set forth. For instance, the E911 emergency system of the United States came forth as a result of the Federal Communication Commission's (FCC) issued E911 regulations.
E911 sought to alleviate the problem of locating mobile telephone users during an emergency call in two phases. In the first phase, E911 sought to establish selective routing of an emergency call from any device, whether landline, wireless, or voice over IP (VoIP), to a PSAP nearest to the caller. Additionally, the first phase sought to provide location information associated with the caller irrespective of the device used in placing the emergency services call. The first phase required that the location of the nearest licensed wireless base transceiver station (BTS) be provided for a licensed wireless emergency caller. The second phase required service providers to identify the location of licensed wireless callers to within a specified distance of the actual location from where the emergency call originated.
In response, licensed wireless networks now support various standardized methods for determining the location of the caller. These methods typically include location estimates based on latitude and longitude coordinates of the caller determined through Assisted GPS (AGPS), Angle of Arrival (AOA), Enhanced Observed Time Difference (E-OTD), Cell Identity plus Timing Advance (Cell ID+TA), and Time Difference of Arrival (TDOA) techniques. These techniques involve interaction between the subscriber's wireless device and systems in the network and generally are dependent on measurements of the licensed radio access network (RAN) signals from the wireless device. A particular service provider may implement one or more of these techniques in its network in order to determine the latitude and longitude coordinates of the caller.
However, new wireless communication technologies continue to emerge that require integration with the aforementioned emergency response systems and location based services. One such technology is an integrated communication network for allowing user equipment of a first communication network to seamlessly communicate through a second different communication network. An example of an integrated communication system is the universal mobile access (UMA, also known as “unlicensed mobile access” and “generic access”) architecture which in one implementation permits a licensed wireless communication device to communicate over an unlicensed wireless network. In this manner, the location based techniques discussed above for the licensed wireless networks cannot be used when the communication device is communicating over the UMA network as opposed to the licensed RAN. This leads to the problem of how to determine the location of the user equipment when it is operating in UMA mode.
Furthermore, while the E911 solution for a licensed wireless communication device provides location information accurate to within a specified distance (e.g., latitude and longitude coordinates), a need nevertheless exists for more specific location information. Specifically, providing emergency responders with a civic address similar to those provided through wired landline services as opposed to the latitude and longitude coordinates of licensed wireless networks would allow quicker response times in emergency situations.